how to troubleshoot P0420 code on Toyota Corolla E170 (2013-2019)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the battery to ensure safety during the repair process.
• Tools Required: OBD-II scanner, multimeter, infrared thermometer, socket set, jack and jack stands.

2. Inspect and Replace Oxygen Sensors

• Remove the Front Oxygen Sensor:
  • Locate the front (upstream) oxygen sensor.
  • Disconnect the electrical connector.
  • Use a wrench to unscrew and remove the sensor.
• Install the New Oxygen Sensor:
  • Apply anti-seize compound to the threads of the new sensor.
  • Screw in the new sensor by hand and then tighten with a wrench to the manufacturer's specified torque (typically around 30 lb-ft).
  • Reconnect the electrical connector.

3. Inspect and Replace Catalytic Converter

• Remove the Exhaust System Components:
  • Locate the bolts securing the catalytic converter to the exhaust system.
  • Use a socket set to remove these bolts and disconnect the exhaust sections if necessary.
• Remove the Catalytic Converter:
  • Unclip any heat shields if present and carefully remove the catalytic converter from its mounting.
• Install the New Catalytic Converter:
  • Position the new catalytic converter in place and secure it using new gaskets if required.
  • Reattach the exhaust sections and tighten all bolts to the specified torque.

4. Clear Codes and Test Drive

• Reconnect the battery and use the OBD-II scanner to clear the P0420 code.
• Take the vehicle for a test drive to ensure that the check engine light does not reappear and that the engine operates smoothly.